[Mesa-dev] [PATCH] dri3: Only update number of back buffers in loader_dri3_get_buffers

[Sergii Romantsov]

Hello,
with my simple tests it works, but have some remarks (but don't have much
experience with dri3):

1. It looks little dangerous to move logic of destroying buffers and seems
in your version we are loosing some logic with 'busy' and 'num_back'
2. And also looks like buffers just will not be destroyed on time for some
cases.
3. From my opinion it will be safer to use in function 'dri3_get_buffer'
call (with my patch):
 'dri3_fence_await(draw->conn, NULL, buffer)' instead of
'dri3_fence_await(draw->conn, draw, buffer)'

On Fri, Apr 27, 2018 at 6:56 PM, Michel Dänzer <michel at daenzer.net> wrote:

> From: Michel Dänzer <michel.daenzer at amd.com>
>
> And only free no longer needed back buffers there as well.
>
> We want to stick to the same back buffer throughout a frame, otherwise
> we can run into various issues.
>
> Bugzilla: https://bugs.freedesktop.org/105906
> Fixes: 3160cb86aa92 "egl/x11: Re-allocate buffers if format is suboptimal"
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> ---
>
> Sergii, Eero, here's an alternative fix which I think is cleaner, can
> you test it?
>
>  src/loader/loader_dri3_helper.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/src/loader/loader_dri3_helper.c b/src/loader/loader_dri3_
> helper.c
> index 23729f7ecb2..6db8303d26d 100644
> --- a/src/loader/loader_dri3_helper.c
> +++ b/src/loader/loader_dri3_helper.c
> @@ -420,13 +420,6 @@ dri3_handle_present_event(struct
> loader_dri3_drawable *draw,
>
>           if (buf && buf->pixmap == ie->pixmap)
>              buf->busy = 0;
> -
> -         if (buf && draw->cur_blit_source != b && !buf->busy &&
> -             (buf->reallocate ||
> -             (draw->num_back <= b && b < LOADER_DRI3_MAX_BACK))) {
> -            dri3_free_render_buffer(draw, buf);
> -            draw->buffers[b] = NULL;
> -         }
>        }
>        break;
>     }
> @@ -559,7 +552,6 @@ dri3_find_back(struct loader_dri3_drawable *draw)
>     /* Check whether we need to reuse the current back buffer as new back.
>      * In that case, wait until it's not busy anymore.
>      */
> -   dri3_update_num_back(draw);
>     num_to_consider = draw->num_back;
>     if (!loader_dri3_have_image_blit(draw) && draw->cur_blit_source !=
> -1) {
>        num_to_consider = 1;
> @@ -1815,6 +1807,7 @@ loader_dri3_get_buffers(__DRIdrawable *driDrawable,
>  {
>     struct loader_dri3_drawable *draw = loaderPrivate;
>     struct loader_dri3_buffer   *front, *back;
> +   int buf_id;
>
>     buffers->image_mask = 0;
>     buffers->front = NULL;
> @@ -1826,6 +1819,16 @@ loader_dri3_get_buffers(__DRIdrawable *driDrawable,
>     if (!dri3_update_drawable(driDrawable, draw))
>        return false;
>
> +   dri3_update_num_back(draw);
> +
> +   /* Free no longer needed back buffers */
> +   for (buf_id = draw->num_back; buf_id < LOADER_DRI3_MAX_BACK; buf_id++)
> {
> +      if (draw->cur_blit_source != buf_id && draw->buffers[buf_id]) {
> +         dri3_free_render_buffer(draw, draw->buffers[buf_id]);
> +         draw->buffers[buf_id] = NULL;
> +      }
> +   }
> +
>     /* pixmaps always have front buffers.
>      * Exchange swaps also mandate fake front buffers.
>      */
> --
> 2.17.0
>
>


-- 
Sergii Romantsov
GlobalLogic Inc.
www.globallogic.com
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